Clear plastic (polystyrene) boxes should not deteriorate and attack the finish on shells, but what you put in the bixes (what you mount the shells on inside the boxes) can be a problem. Avoid any kind of "foam rubber" or plastic foam products. Even though such products today are more stable than they were 20 years ago, some of them can still decompose, releasing acids that can dull the gloss on a cowrie or olive shell. In old collections I have purchased, some foam inserts have deteriorated to the point where they were gummy, or else hard and brittle. And, in one old collection , many of the shells mounted on this kind of material were badly damaged. In fact, some of the thinner specimens, like Epitoniidae, actually had holes eaten through the underside of the shell, where it was in contact with the foam. Personally, I like surgical cotton, which I buy in 1-pound rolls. However, some folks distrust even cotton, and use some kind of glass wool or fiberfill. Paul M.